The Men’s Running singlet is made completely of a sheer Summer weight, Italian fabric called Air-Pass, this Running specific fabric will pull moisture from your body, trap it between two sheer fabric layers and use your sweat to keep you cool while it’s drying. Friction is another issue for long distance running, just as the fabric is specific to running so is the cutting of the garment, the ergonomic design was chosen to limit any irritation in the running range of movement. We have oversized arm openings and a thin curved back panel to limit under arm rubbing from arm swing. These Running singlet’s have already been on the backs of Runners finishing the Berlin and Boston marathons.